[Cuog]

First I'm pretty sure you don't KNOW whats in the kit, they may go back to giving you a bunch of gears and saying make it yourself.

Banebots is about as simple as it gets, however the reliability is debatable.
There are other simple single speed transmissions that will be right about as easy, you have to define all of the points that you want a gearbox to have, then identify the gearing needed and how well each system that you find will work for that. kit gearboxes will also be very simple to utilize.